Rotary tools for performing a plurality of operations on a workpiece have been known for many years. For example, a U.S. Pat. No. 3,346,894 of Lemelson entitled, “Apparatus For Controlling Rotary and Longitudinal Movements Of A Combination Tool Carrying Spindle,” discloses a combination tool including a drill and a further portion for performing a secondary operation on a workpiece during or immediately following the cutting of a hole in the workpiece with the drill. As disclosed, the rotary drill includes a twist drill connected to a tapered head. The tapered head is connected to a shank and includes a plurality of replaceable blades.
A more recent U.S. Pat. No. 5,282,705 of Shiga et al. is entitled “Burnishing Drill.” The Shiga et al. patent discloses a cylindrical shank and a drill body connected to the shank. Drilling edges, reaming faces and reaming edges are formed on a first reduced diameter portion, a second reduced diameter portion and a third reduced diameter portion located at a foremost end of the drill body respectively. The reaming faces which are located axially at rearward positions of the drilling edges and the reaming edges extend radially outward from the foremost end of the drill and incline axially in the rearward direction with respect to the rotational direction. Since an inner surface of the hole is drilled and reamed by the drilling edges and the reaming edges can be further smoothed by the reaming faces, the surface roughness of the finished hole can be improved.
Notwithstanding the above, it is presently believed that there may be a commercial market for an improved rotary drill in accordance with the present invention. There should be a commercial market for such tools since they offer improved cutting by a frusto conical file which is durable and which provides an improved cutting edge over an extended period of time. Further, the rotary tools in accordance with the present invention can be manufactured with different degrees of coarseness for different purposes and at a competitive price.
In addition, the rotary tools in accordance with the present invention are made of a hard steel and have a high resistance to breakage and are capable of maintaining a sharp cutting edge and are resistant to fracture. Further, it is presently believed that the composition of a rotary tool in accordance with the present invention can be adjusted to optimize the performance of the tool with respect to the composition of the workpiece.